HGPRTase phosphoribosyltransferase

The free bases of the purines can be salvaged to spare de novo synthesis. The only hard thing is remembering what the names stand for. HGPRTase is hypoxanthine-guanine phosphoribosyltransferase, and it makes both IMP and GMP. A separate enzyme exists for the salvage of adenine. The salvage pathways are included in Fig. 19-1. 

The Lesch-Nyhan syndrome is caused by a deficiency of the phosphoribosyltransferase that is involved in the salvage pathway for hypoxanthine and guanine (HGPRTase). The accumulation of P-Rib-PP stimulates purine biosynthesis. 

Salvage pathway is a useful term to refer to that collection of biochemical reactions whose transformations result in the phosphorylation of purines. As a consequence of this phosphorylation, purines are not secreted by cells but, in fact, are returned to the cellular metabolic pool. One of these salvage enzymes is hypoxanthine-guanine phosphoribosyltransferase (HGPRTase),... 

The abbreviations are as follows HGPRTase = hypoxanthine-guanine phosphoribosyltransferase P TR ase = nucleoside phosphotransferase APRTase = adenine phosphoribosyltransferase ASS3m-Lyase = adenylosuccinate synthetase-lyase. 

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